1. Field of the Invention
The present invention relates to an injection stretch blow molding apparatus and method, and particularly to an injection stretch blow molding apparatus and method provided with a transfer station which transfers preforms from an injection molding station to a blow molding station.
2. Description of the Prior Art
An injection stretch blow molding apparatus and method has previously been disclosed in Japanese Patent Application Laid-Open No. 8-132517 by the applicant of the present invention.
The above invention has an injection molding station in which a preform is injection-molded, a blow molding station in which the preform is stretch blow molded, and a transfer station which transfers preforms from an injection molding station to the blow molding station.
In the injection molding station, a plurality of preforms are injection-molded simultaneously, each preform is cooled by an injection molding core mold, and after the preform has cooled to a temperature at which removal is possible, the preform is removed from the injection core mold by a removal section.
In the transfer station, the plurality of simultaneously injection-molded preforms are, either in a single operation or divided into a plurality of operations delivered to a blow molding station. In detail, there is provided a receiving mechanism which receives a plurality of simultaneously molded preforms, and an inverting and delivering mechanism which, either in a single operation or divided into a plurality of operations, inverts the preforms received by the receiving mechanism from the upright state and delivers them to the blow molding station.
In the blow molding station, preforms received from the transfer station are carried by a carrying member which is circularly carried. The preforms are carried into a blow molding section in batches numbering fewer than the number of preforms molded simultaneously through a heating section and a standby section, then are blow-molded.
With this system, preforms are molded with a reduced injection molding cycle time while maintaining an adequate cooling time. Moreover, the operating efficiency of the blow cavity mold can be increased.
The present invention is a further development of this injection stretch blow molding apparatus and method.
The object of the present invention is to provide an injection stretch blow molding apparatus and method which allows more time between the removal of a preform from the injection molding station and the transfer of the preform to the blow molding station. Moreover, the influence during the blow molding due to the thermal distribution applied to the preform during injection molding is further reduced.
Another object of the present invention is to provide an injection stretch blow molding apparatus and method in which the operating time of the receiving mechanism which receives the preforms from the injection molding station can be reduced. Furthermore, the receiving mechanism can rapidly be ready to stand in the receiving position, in accordance with the operating cycle time of the injection molding station.
A further object of the present invention is the efficient cooling particularly of a thick preform.
An injection stretch blow molding apparatus of the present invention comprising:
an injection molding station in which preforms are injection molded in an upright state with neck portions thereof facing upward;
a blow molding station in which carrying members supporting the preforms are circularly carried and the preforms are stretch blow molded into containers in an inverted state;
a transfer station for inverting the preforms removed from the injection molding station and for transferring the preforms to the carrying members of the blow molding station; and
wherein the transfer station includes:
a receiving mechanism for receiving the preforms from the injection molding station in the upright state;
an inverting and delivering mechanism for inverting the preforms at least one at a time and for delivering the preforms in the inverted state to the carrying members; and
a movement mechanism disposed between the receiving mechanism and the inverting and delivering mechanism, and for moving the preforms from the receiving mechanism to the inverting and delivering mechanism in the upright state.
According to one aspect of the present invention, in the transfer station, a movement mechanism is provided between the receiving mechanism and the inverting and delivering mechanism. In this way, the movement mechanism functions as a buffer, and more time can be taken between removing the preforms from the injection molding station and delivering them to the blow molding station. Particularly for preforms of thick construction, this allows the temperature difference between the inner and outer walls to be minimized, and provides time for gentle cooling, thus reducing the unfavorable influence at the time of blow molding caused by the temperature distribution applied to the preform during the injection molding process. Moreover, immediately after delivering the preforms to the movement mechanism, the receiving mechanism can be returned to the receiving position for the next preforms. As a result, the flexibility of timing for removing preforms from the injection molding station is increased. It should be noted that the delivery of preforms from the transfer station to the blow molding station is achieved by the movement mechanism, the inverting and delivering mechanism, and the carrying members, without involving the receiving mechanism.
The receiving mechanism preferably has N numbers of first supporting members for receiving and supporting N (Nxe2x89xa72) numbers of preforms simultaneously injection molded in the injection molding station. Furthermore, the movement mechanism preferably has at least N second supporting members.
By the N number of first supporting members and N number of second supporting members, the N number of preforms simultaneously injection molded can be transferred from the receiving mechanism to the movement mechanism in a single operation.
The blow molding station has a blow molding section for blow molding n (1xe2x89xa6n less than N) number of the preforms into n number of containers at a time; and
wherein the inverting and delivering mechanism preferably has n number of third supporting member(s) inverting and delivering the same n number of the preforms as are to be simultaneously blow molded by the blow molding station. If N number of preforms are delivered simultaneously, the number of the third supporting members is increased. Therefore, by delivering a number n appropriate to the blow molding cycle, the number of the third supporting members can be reduced. It should be noted that the time required for delivery in this way is increased. Nevertheless, since the receiving mechanism mechanism can be immediately returned to the receiving position.
The movement mechanism preferably has a circulatory movement means circulating and moving at least N numbers of second supporting members. This structure easily moves the second supporting members from the receiving position of the receiving mechanism to the delivery position leading to the inverting and delivering mechanism.
The circulatory movement means preferably have a first endless moving member circulating in a vertical plane, and at least N numbers of second supporting members fixed thereto. In this way, the space required for the circulatory movement means can be kept to a minimum. It should be noted that if the first endless moving member has an upper movement region provided with the receiving position and the delivering position, the preform can be transferred in the upright state.
The circulatory movement means may also have a second endless moving member circulating in the horizontal plane, and at least N numbers of second supporting members fixed thereto. In this way, the second endless moving member may have first and second movement regions mutually parallel in the horizontal plane, and a large number of preforms can be transferred in the upright state. As a result, the ability of the circulatory movement means to function as a buffer is increased, and a longer cooling time is available.
Each of the N numbers of second supporting members preferably has a depression receiving and supporting the bottom of the preforms in the upright state.
By this means, without being affected by the shape of the preform, it can be securely supported. In particular, secure support is possible in the case that the body portion is fatter than the flange portion of the neck portion of the preform.
Each of at least the N numbers of second supporting members may have a pair of opening and closing members biased toward the closed position by a resilient member. This pair of opening and closing members supports a portion under the neck portion of the preform. In this way, the support and removal operations of the preform may be simplified.
The injection molding station may have:
two injection core molds;
a rotary member which rotates around a rotating shaft and supports the two injection core molds at positions opposite to each other with the rotating shaft in the center;
an injection molding section including one injection cavity mold which is clamped alternately with one of the two injection core molds for injection molding the N numbers of preforms; and
an ejecting section for ejecting the N numbers of injection molded preforms from the other of the two injection core molds which is carried out of the injection molding section by rotation of the rotary member. In this case, the ejecting section may comprise N numbers of cooling pots into which are inserted the N numbers of preforms supported by the other of injection core molds; and
elevator means for raising the N numbers of cooling pots to a position at which the N numbers of preforms are inserted and for lowering the N numbers of cooling pots before the N numbers of preforms are ejected.
With this construction, the preforms can be cooled from the outside by the cooling pots in the removal section, and in particular the cooling efficiency for thick preforms can be further increased.